I just went pass this site. It says that sunrise has comfirm that there will be an installment of a 3rd gundam seed. Not
sure if its call Seed Eternity and there is not yet of any posted info. for it in their main site as well.
The site its japanese, and I cant translate very well, but it seems that the gundam seed 3 stuff is all going to begin
in this fall.
Here is the site that I got this info.
http://d.hatena.ne.jp/moonphase/20051223